The requirement in the electronics industry for large numbers of complex wiring harnesses for use in electronic systems has led manufacturers to create many means of electrical harness fabrication in an effort to achieve the most cost-effective methodology. However, today's spectrum of solutions, including automated mass wiring techniques for industries that require large numbers of identical harnesses, i.e., the automobile industry, are very costly in the majority of cases where limited quantities of harnesses are required. Lacking a better solution, the electronics industry has for the most part maintained a system of fabrication based on unassisted manual wiring. This manual production method has been to assemble electrical wire harnesses on shop aides called "formboards".
One harness assembly method is known as the "cut to length" method. The actual length and type of wire to be cut is established during the initial development of the harness. Next the appropriate designation characters are hot stamped onto the wire at customer specified intervals and other wire identification such as tabs, sleevings and identifying nomenclature are attached. Identified wires are then sorted by placing them on a rack according to the first end plug to which they will later be terminated. Once the racking is completed the grouped wires are lugged or soldered into the respective connectors, called "first end" plugs, according to information provided by a wiring document. Preassembled first end plugs are then consolidated to form a harness complement and are shipped to the formboard upon schedule demand.
The harness to be assembled requires preprinted wire cards, or equivalent, to supply information on the formboard wire routing and second end termination. The formboard sequence starts by placing the first end plug on the board and manually sorting through the wire bundle to select a particular wire, routing the selected wire according to the information on the wire cards, trimming the wire to an exact length, and then terminating that wire with a lug or pin at the second end location. These events are repeated until all harness wires have been installed and then the completed assembly is inspected. This process is time-consuming when left up to the discretion of the operator, since a significant amount of time is spent in looking for the appropriate wires. A more structured method of harness manufacture is not currently available and present methods are limited to the necessity of the operator getting information from wiring documents called "wire cards".
Prior to wrapping and tie-up, the entire harness is lifted from the formboard and continuity tested by means of automatic circuit test equipment, commonly manufactured by DITMCO and others. When errors are detected the test machine reaction is to print out a series of symbolic codes representing the error location. These error codes must be deciphered, and the results along with the harness are returned to the formboard for correction. Recycling of the harness through automatic circuit test and repair occurs until the harness is error-free.
Once the wire harness has been certified as correct, it is remounted on the formboard for final assembly. Each plug receives packing to insure a certain amount of wire strain relief at the point of pin insertion. The cables are also tied with lacing to secure the loose collection of wires into tight bundles. Labels are then affixed identifying the various branches of the cable to identify wire card callouts. Final inspection follows checking for correct nomenclature, recessed pins, and general customer acceptance specifications. Thereafter the harness is shipped as a sold item ready for installation.